Someone please tell me that this is wrong, so that I feel better about myself.

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LET'S SAY YOU HAVE A CAR. I DON'T REALLY CARE WHAT TYPE OF CAR. LET'S SAY YOU HAVE A HUMMER. OR MAYBE A HAMMER. A TOYOTA HAMMER. WHO CARES.

ANYWAYS, YOUR CAR STARTS ACCELERATING TOWARDS MADAGASCAR. WHY? DON'T ASK ME, YOU'RE THE ONE DRIVING A HAMMER. Your velocity is positive and it is increasing at a high rate. Or something like that. You have increasing acceleration.

Now, you're still increasing your velocity on the motorway, but you realise the speed limit is actually 100km/h and you have to stop pressing X to win. You're not blue and cool. Sorry. Therefore, your velocity is tapering off and reaching a constant speed of 100km/h. THIS IS DECELERATION. YOUR ACCELERATION IS NOT NEGATIVE. YOUR SPEED IS NOT NEGATIVE. NOT NEGATIVE. DERIVATIVE

Once you reach Adelaide, you check your map again and realise that the best way to get to Madagascar is to drive back to Melbourne and catch a plane. Hurrrrrrrr. Well, anyways, you start driving back. BUT WAIT YOU'RE NOT GOING TO MADAGASCAR YOU'RE GOING THE WRONG WAY SEE THAT LAKITU IS SHOWING THAT WRONG WAY SIGN DURRR so your velocity is negative, therefore your acceleration is negative. HOWEVER. You are increasing your velocity at an increasing rate, so you have increasing negative acceleration. YES ITS IN THE OPPOSITE DIRECTION, but it's increasing.

When you go onto this motorway again and your velocity reaches 100km/h again (LOL IT'S LIKE A SKILL CEILING IN A FPS) you will be experiencing NEGATIVE DECELERATION. OH DEAR, YOUR HAMMER ISN'T A RACECAR. WHY DIDN'T YOU DRIVE A GOON TRUCK. WITH SAWBLADES. AND ROCKETS. GEEZ.

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LET'S SAY YOUR CAR HIT A RED LIGHT, OR FLOATING PLATFORM. THIS MEANS YOU HAVE TO SLOW DOWN. OH DEAR. THIS IS ALSO DECELERATION. IF IT'S FROM ADELAIDE, IT'S IN THE NEGATIVE DIRECTION. YES, THERE IS NEGATIVE DECELATION.

"Acceleration is defined strictly as the time rate of change of velocity vector. Deceleration, on the other hand, is acceleration that causes reduction in "speed". Deceleration is not opposite of acceleration. It is certainly not negative time rate of change of velocity."